Same here. The perception is that you're "cheating." The reality is, you're helping everyone get to their destination faster. People don't see that because you're now in front of them. But what about the 1, 2, 50 bikes that were in front of them that are now already at their destination because they filtered?
I try to argue my point with these analogies:
Are HOV lanes good or bad? The answer is always good because there are more people in less cars. This gets people to their destination more efficiently. Followup question... would you get to work faster if everyone on the road drove tractor-trailers, or smart cars? Obvious, right? Again, the higher the ratio of people vs. vehicle space, the faster they arrive at their destination. The road is a limited resource, and one solution to congestion is using it more efficiently.
Now these are simple points that no sane person will argue against. The gotcha is that filtering utilizing unused space on a limited resource. They're already built, FREE, HOV lanes! Legalizing it and educating the public will promote riding and get EVERYONE to their destination faster. People with half a brain will see this logic because it's friggin' bulletproof. Unfortunately, most people don't possess this.
It should be legal for slow/sitting traffic, period.